Automatic furnace control



June 17, 1930. H ow 1,764,715

' AUTOMATIC FURNACE CONTROL Filed Jul 28,, 1926 2 Sheets-Sheet 1 [NVEN TOR.

A TTORN ]L V8 June 17, 1930. H. H. DOW ,7 ,71

AUTOMATIC FURNACE CONTROL Filed my 28, 1926 2 Sheets-Sheet 2 I INVENTOR. .flerwz J1. 170w ATTORNE J.

Patented June 17, 1930 UNITED STATES PATENT OFFICE HERBERT DOW, OF MIDLAND, MICHIGAN, ASSIGNOR TO THE CHEMICAL COM- i PANY, OF MIDLAND, MICHIGAN, A CORPORATION OF MICHIGAN Application filed July 28,

This invention relates more particularly to control of furnaces for boilers and other uses. Efforts have heretofore been made to effect an automatic control of furnace firing '5 Where a liquid fuel is used, the temperature being the governing factor, but a system adapted to regulate with respect to efficiency of combustion, and applicable generally irrespective of the character of fuel used, is

highly desirable.

To the accomplishment of the foregoing and related ends, the invention, then, consists of the features hereinafter described and particularly pointed out inthe claims, the following description and the annexeddrawing setting forthbut oneof various forms in which the principle of the invention may be used.

In said annexed drawing Fig. 1 is a diagrammatic representation of one embodiment of my invention; and Fig. 2 is a similar showing of certain details.

In its general aspects, the invention involves a means forfeeding a fuel to a combustion zone, and a means for feeding the oxygen for combustion, one or the other or both of such feed means being controlled by the character of the combustion gases.-

In the illustrative form shown, a boiler setting 1 comprising a primary combustion chamber 2 with a tubular boiler unit 3,, and another combustion chamber; with a second boiler unit 5, followed by a further unit 6, steam-connected or separate as desired, is provided with feeders 7,, 8, supplying powdered fuel from-a bin 9 through ducts 10, 11. Air for combustion is supplied from a blast fan 12 through tuyeres 13, being pref- AUTOMATIC FURNACE CONTROL 1926. Serial No. 125,553.

through a heat exchanger 20 to a pump 21, preferably of reciprocating plunger type and driven by a belt, gearing or other suitable means. From the'pump 21, a discharge pipe 22 on the same side of the plunger leads to a discharge port or nozzle 23. A generally similar nozzle 24 is placed in opposed relation to the nozzle 23 or at least in such a position as to act oppositely on a movable element 25. The discharge port or nozzle 24 connects with the pump 21, and from the same side of the plunger a pipe 26 leads from the atmosphere through'the heat exchanger 20. In this manner a gas of constant quality is conveniently secured for the opposing nozzle. However, some other gas of constant quality could likewise be used. By theme of a single pump acting on both air and the combustion gases an equalization of feed is realized which would otherwise be diflicultly attained unlessa plurality of pumps were employed. However, detail changes in this re spect may be made as preferred.

The movable member 25 preferably takes the form of a rotor having blades such that in the path of the discharge fromthe nozzles 23 and 24, the rotor will be correspondingly turned, and as will be seen from the arrangement of the pumping means, the blasts of combustion gases from the furnace and the blasts of air respectively will be pumped in alternation so as to impinge upon the movable element 25. A train of gearing 27 from the movable member 25 operates a quadrant gear 28, and mounted inconnection with the latter is a pivoted arm 29, there being a lostmotion connection between the quadrant gear and thearm, for instance by the-arrangement of spaced lugs 30 on the quadrant through which adjustable set screws 31 are placed so.

to bear against the respective sides of the arm 29. In this manner, the set screws I may be so adjusted as toallow of average movements being communicated from the rotor 25 wlthout affecting the arm 29, but on exceeding the so predetermined range, the r arm 29 will be correspondingly swung aside. Located in relation with the arm 29 is a series of contacts of a rheostat R, this being electrically connected with a motor driving the fan 12, for'instance such motor may be of shunt wound type and the rheostat B may control the field F thereof, current being 4 taken from mains 32 which are connected with a suitable source.

are drawn off by way of pipes 17 (r 18 and passing through the heat exchanger 20 are averaged in temperature with air coming through the air pipe, and the'pump 21 forces blasts alternately .through the nozzles 23- and 24. By reason of the difference in efiective mass of the combustion gases in accordance with the carbon dioxide content, a blast of combustion gas .will tend, other things being equal, to drive the rotor 25*toa greater extent than a corresponding blast of air. By initially adjusting the angle of attack of the nozzles 23 and 2 1 respectively, a setting may be made in which the motions imparted by the blasts of flue gas and air are equal for some particular optimum carbon dioxide content as checked by chemical analysis of the flue gas, and at which setting, the to and fro movements of the quadrant being equal, no progressive movement of the rheostat arm will occur and no consequent change in fan speed will be thereby caused. Instead the fan speed and air supply will remain constant. Such predetermined setting will then constitute the standard for the operation of the device, which may then act to 'maintainthat standard in subsequent operations, since when the relative amount of carbon dioxide as delivered through the jet 23 increases, it will tend to overrun the rotor 25 as compared with the return movement occasioned by the air jet 24. Conversely, if the proportion of carbon dioxide as delivered from the furnace products by the jet 23 should decrease,-the effect upon the rotor 25 will be less than that of the air blast from jet 24, and correspondingly the rotor will run the train of gearing in that direction cumulatively to move the arm 29 across the rheostat and regulate the motor accordingly. It will thus be seen thatwith change in carbon dioxide content as expressed in its effect in causing motion of the rotor as compared with the motion from the air blasts, the rheostat will be moved to accelerate, or to slow down the fan supplying the air to the combustion chamber.

Increase in carbon dioxide will cause an acceleration of the fan and a consequent in crease in air supply to the combustion zone, while decrease in the proportion of carbon dioxide jetted upon the rotor will cause the rheostat to slow down the motor and lessen the feed of air to the furnace.

- Such changes in air supply will tend to restore the carbon dioxide content in the fluegas to the optimum value, and as soon as that value is reached, the equality of rotative effects of the two jets will have been restored and the quadrant will oscillate through equal arcs and no further progressive movement of the rheostat arm will ensue until a change in Co content demands it,

but it will remain in the new position corresponding to the new rate'of air supply. It

will be seen therefore that the device will function to maintain optimum furnace conditions over the practicable range of boiler or furnace rating or operating duty since if the fuel feed be changed either for increased or decreased duty, the CO content being thereby affected, the automatic device will change the air supply accordingly and restore the optimum condition.

WVhile for illustration, I have shown the feed control as connected to the air supply, I contemplate in some instances controlling the fuel supply. As alrule however, it is more convenient to effect the control on the air supply on thegeneral lines indicated. This particular form of control system may also be installed in existent furnaces where equipment as designed for handling the fuel is of widely varied type. Moreover instead of controlling the drive of a fan supplying the air, I may in some cases control a damper supplying the air for the combustion zone. Where it is preferred to control the fuel instead of or along with the air, this may be.

Other modes of applying the principle of my invention may be used, change being;

made in the features set forth, provided the means or steps stated in any of the following claims or the equivalent of such be employed.

I therefore particularly point out and distinctly claim as my invention 1. A method of feeding a combustion zone, which comprises translating into a differential rotative mechanical motion the dynamic energy of opposingly operating jets of the gaseous combustion products and of a gas of uniform composition, and thereby gauging the feed of a component supplied to the combust-ion zone.

2. A method of feeding a combustion zone, which comprises translating into a differential rotative mechanical motion the dynamic energy of opposingly operating jets of the gaseous combustion products and of a gas of uniform composition, and thereby gauging the blowing of air to the combustion zone.

'3. A method of feeding a combustion zone, which comprises translating into a difierential rotative mechanical motion the dynamic energy of opposingly perating jets of the gaseous combustion products and of air respectively, and thereby gauging the blowing of air supply to the combustion zope.

l. In a method'of feeding a combustion zone by controlling the ratio of fuel and air 0 supply, the steps which consist in directing alternate opposed jets of air and flue gas, respectively, upon a member rotatable in opposite directions by the dynamic effect of said jets and employing excess rotation of said rotatable member in one said direction to initiate action of mechanism controlling said rotation. 5. In apparatus of the character described, including a furnace and means for supplying a combustion component thereto, means for controlling the supply, said control means including a nozzle delivering a propulsive jet of gases from the combustion chamber, and a member located in the range thereof and movable in response to such jet. I

6. In apparatus of the character described, including a furnace, means for controlling the air supply thereto, said means including a nozzle delivering a propulsive jet of gases 0 from the combustion chamber and a member located in the range thereof and movable in response to such jet.

.7. In apparatus of the character described, including a furnace and means for supplying 'a combustion component thereto, means for controlling the supply, said control means including opposed nozzles, one delivering a jet of gases from the combustion chamber and the other delivering a jet of a gas of con- 40 stant quality, and a member located in the 'range thereof and differentially movable in response to such jets. 8. In apparatus of the character described, including a furnace, means for controlling the air supply thereto, said means including opposed nozzles, one delivering a jet of gases from the combustion chamber and the otherdelivering a jet of a of constant quality, and a member located in the range thereof 5 and differentially movable in response to such jets. a

9. In apparatus of the character described, including a-furnace and means for supplying a combustion component thereto, means for controlling the supply, said control means including opposed nozzles, one delivering a jet of gas from the combustion chamber and the other delivering ajet of a gas of constant quality, and a rotatable member located in the range thereof and regulating the power operating the supply means.

l v 10. In apparatus of the character described, including a furnace, means for controlling the air supply thereto, said means including opposed nozzles, one delivering a jet of gases from the combustion chamber and the other delivering a jet of a gas of constant quality,

"and a rotatable member located in the range thereof and regulating the power operating the supply means.

11.- In apparatus of the character described, including a furnace and means for supplying a combustion component thereto, means for controlling the supply, said control means including opposed nozzles, one delivering a jet of gas from the combustion chamber and the other delivering a jet of a gas ofconstant quality, a rotatable member located in the range thereof,'a rheostat actuated by said rotatable member, and a motor gOXGl'IlQCl by said rheostat and operating the aforesaid supply means. a

12. In apparatus of the character described, including a furnace and means for supplying air thereto, means for controlling the supply, said control means including opposed noz-' zles, one delivering a jet of gas from the combustion chamber and the other delivering a jet of "a gas of constant quality, a rotatable 7 member located in the range thereof, a rheo stat actuated by said rotatable member, and a motor governed by said rheostat and operating the aforesaid air-supply means.

13. In apparatus of the character described. including a furnace" and means for supplying a combustion component thereto, means for controlling the supply, said control means including opposed nozzles, means for discharging from said nozzles respectively a jet of gas from the con'ibustion' chamber and a jetof a gas of constant quality, means for equalizing the temperature of such gases, and, a-rotatable member located in the range of said nozzles and regulating the power operating the aforesaid supply means.

14. In apparatus of the character described, including a furnace and means for supplying air thereto, means for controlling the supply, said control means including opposed nozzles, means for discharging from said nozzles respectively a jet of gas from the combustion chamber and a jet of a gas of constant quality, means for equalizing" the temperature of such gases, and a rotatable member located in the range of said nozzles and regulating the power operating the aforesaid supply means.

15. In apparatus of the character described, includinga furnace and means for supplying a COD'llJllSt-lOII component thereto, means for controlling the supply, said control means including opposed nozzles, means for discharging from said nozzles respectively a jet of gas fromthe combustion chamber and a jet of a gas of constant quality, means for equaiizing the temperature of such gases, a rotatable member located-in the rear of said nozzles, a rheostat actuated by said rotatable member, and a motor governed by said rheostat and operating the aforesaid supply means.

16. In apparatus of the character described. including a furnace and means 'for supplying air thereto, means for controlling the supply, said control means including opposed nozzles, means for discharging from said nozzles respectively ajet of gas from the combustion chamber and a jet of a gas of constant quality, means for equalizing the temperature of such gases, a rotatable member located in the range of said nozzles, a rheostat actuated by said rotatable member, and a motel-governed by said rheostat and operating the aforesaid supply means.

17. In apparatus of the character described, including a furnace and means for supplying a combustion component thereto, means for controlling the supply, said control means including opposed nozzles, means for discharging from said nozzles respectively a jet of gas from the combustion chamber and a jet of a gas of constant quality, means for equalizing the temperature of such gases. a rotatable member located in the range of said nozzles, a rheostat, an adjustable lostmotion connection between said rotatable member and said rheostat, and a motor governed by said rheostat and operating the aforesaid supply'means.

18. In apparatus of the character described, including a furnace and means for supplying air as a combustion component thereto, meansfor controlling the supply, said control means including opposed nozzles, means for discharging from said nozzles respectively a jet ot gas from the combustion chamber and a jet of a gas of constant quality, means for equalizing the tem wrature of such gases, a rotatable member located in the range of said nozzles, a rheostat, an adjustable lostmotion connection between said rotatable member and said rheostat. and a' motor gorerned by said rhcostat and operating the aforesaid supply means.

19. In apparatus of the character described, including a furnace and means for supplying a combustion component thereto,

means for controlling the supply, said control means including opposed nozzles, means for said control means including opposed nozzles, means for adjusting the position of said nozzles, means for discharging from said nozzles respectively a ct of gas from the combustion chamber and a jet of a gas of constant quality, means for equalizing the temperature of such gases, a rotatable member located in adjusting the position of said nozzles, means for discharging from said nozzles respective- 1y a jet of gas from the combustion chamber and a jet of a gas oi? constant quality, means for equalizing the ten'iperature of such gases,

a rotatable member located in the range of said nozzles, a rheostat, an adj ustable lostmotion connection between said rotatable member and said rheosta't, and a motor verned by said rheostat and operating the aforesaid supply means.

20. In apparatus of the character described, including a furnace and means for supplying air as a combustion component thereto, means for controlling the supply, 

